In an open letter published in several newspapers on Monday, the prime minister of the Netherlands gave immigrants who “refuse” to integrate into Dutch society two options: “Behave normally or go away.”

But observers view the message Mark Rutte repeated in an interview with the Algemeen Dablad newspaper published the same day as less about enforcing social norms and more about luring voters from the the prime minister’s populist far-right opponent who is currently ahead in the polls.

Mr. Rutte’s layered immigration message on Monday also shows the pressure European leaders are under as the “super elections” between incumbents and populist opponents nears. The election in the Netherlands on March 15 will be the first in three countries to see politicians who represent European unity face off against anti-immigrant Euroskeptics, as Sara Miller Llana reported for The Christian Science Monitor.

“The three upcoming elections will test just how powerful populist forces have become in key European nations,” wrote Ms. Llana, mentioning the Netherlands, France, and Germany. “The far right has grown in force in each of these countries, coupling anti-immigrant and anti-European Union sentiment. Yet there are still more politicians who support the European project than don’t, and more people who think the EU is a positive thing than negative.”

In the open letter that ran as a full-page ad in several newspapers, Rutte acknowledged he shared feelings of frustration for immigrants “who fundamentally reject this country.”

“I understand the people who think that if you so fundamentally reject our land, I prefer that you leave,” he said. “As it happens I have that feeling too. Act normal or go away.”

He also mentioned “antisocial people who believe they should always have priority. Who dump rubbish on the streets, and who spit on the conductors on the trains and trams.”

But the leader of the center-right People’s Party for Freedom and Democracy (VVD) said it’s also important not to generalize this frustration against all immigrants.

The solution, he said, is “not to tar everyone with the same brush, or insult or expel whole groups” but to “make it crystal clear what is normal, and what is not normal, in our country. We must actively defend our values.”

The letter didn’t mention Rutte’s far-right opponent for prime minister by name. But Geert Wilders, the leader of the nationalist Freedom Party (PVV), took aim later on Monday at the man he wants to unseat.

He called the prime minister “the man of open borders, the asylum tsunami, mass immigration, Islamization, lies and deception.”

Rutte is seeking to defeat Mr. Wilders and win a third term. He assumed office in 2010, two years after the financial crisis that swept across Europe, and he is credited with steering the Netherlands out of it. But he has seen his popularity slide, with criticisms that include presiding over a “moral crisis,” according to The Guardian.

Wilders has surged in the polls, with some recent surveys showing support for Wilders' PVV nearly equal to VVD ahead of the vote, as The Washington Post reported. But even if Wilders wins the most seats in the Dutch parliament, he isn’t expected to be able to form a coalition. Mainstream parties have vowed not to enter government with Wilders, who was convicted in December of insulting and inciting discrimination against Moroccans. Wilders is appealing the conviction, which he said is “shameful.”

The election result in the Netherlands could foreshadow results in France and Germany later in the spring and fall, respectively.

If she wins, “that would put one of Europe’s harshest Euroskeptics at the head of a country that, as a founding member of the EU, is crucial to the bloc’s continued legitimacy,” writes the Montior’s Llana. “Even if populists don’t win upcoming races, they are setting agendas and dividing the bloc just at a time when the EU needs to stand together,” referring to concerns of Russian meddling, the refugee crisis, and the fallout of “Brexit.”

While it’s not Europe’s most stable moment, says Ian Lesser, vice president for foreign policy at The German Marshall Fund of the United States in Brussels, the pressures of 2016 may have served as a wake-up call.

“And there is some good in that,” he says, especially with the busy electoral schedule this year.

“The large presumption was that this simply could not happen,” he says. “Complacency has been profoundly shaken. … Media, policy institutions, and politicians have realized how out of touch they really are, and that they have to get their finger on the pulse of what people are thinking and likely to do.”